1. Field of the Invention
The present invention relates to an apparatus for attaching top end stops to a continuous slide fastener chain.
2. Description of the Prior Art
One known apparatus for attaching two top ends stops simultaneously to a continuous slide fastener chain is disclosed in Japanese Laid-Open Patent Publication No. 50-60356 published May 24, 1975. The disclosed apparatus includes a punch mechanism having a pair of punch levers with cam surfaces defined on outer lower sides thereof. When the punch levers are lowered, the cam surfaces are engaged by respective rollers to push the punch levers toward each other for thereby clamping top end stops on longitudinal marginal edges of slide fastener stringer tapes in cooperation with a die block disposed between the punch levers. Since the punch levers are forcibly displaced by the rollers, the punch levers are subject to undue stresses and frictional resistance, often failing to clamp the top end stops accurately on the stringer tapes Therefore, some top end stops thus attached may be slightly out of proper posture, and the resultant slide fasteners are of poor product quality. Another problem is that considerable drive forces must be imposed on the punch mechanism in order to attach two top end stops simultaneously in coaction with the rollers. Repeated application of substantial drive forces tends to lower the durability of the punch mechanism in a short period of time.
The two top end stops are gripped between the confronting flat surfaces of the die block and the punch levers at their lower ends, with the lower ends of the top end stops being exposed downwardly As a consequence, upon descent of the punch mechanism toward the longitudinal marginal edges of the stringer tapes, the marginal tape edges are apt to be caught by the exposed ends of the top end stops carried by the punch mechanism, and hence may be not introduced smoothly into the respective top end stops. The lower ends of the die block and punch levers which hold the top end stops together have flat surfaces incapable of guiding the marginal tape edges reliably into the top end stops.
U.S. Pat. No. 4,203,207 issued on May 20, 1980 also discloses a top end stop applicator including a pair of grippers for gripping longitudinal marginal edges of a pair of slide fastener stringer tapes, the grippers being angularly movable apart from each other for successive disengagement of rows of coupling elements Another conventional top end stop applicator shown in U.S. Pat. No. 4,217,685 issued on Aug. 19, 1980 includes a separator having a pair of pointed members. The pointed members are inserted in an element-free space in a slide fastener chain and are laterally moved apart from each other to split two intermeshing rows of coupling elements into individual rows. These mechanisms for separating coupling elements are however disadvantageous in that the mechanisms are complex in structure, and the rows of coupling elements are liable to be separated for irregular lengths since they are separated by the grippers or separators which are laterally shifted from each other. With the coupling element rows separated for uneven lengths, top end stops may not be attached to the marginal tape edges at accurate positions. Inasmuch as the coupling element rows are split in the horizontal plane in which the slide fastener chain lies, the marginal tape edges may be displaced out of exact alignment with top end stops to be attached, and hence the top end stops may not be applied accurately and reliably to the marginal tape edges.